The present invention relates to door opening closures. More particularly, this invention relates to a flexible covering apparatus for large door openings.
Large door openings pose special problems in allowing entry of industrial equipment, such as, trucks, front loader, etc. while preventing the unwanted entry of animals such as birds, deer, etc. For example, road-side buildings housing materials, such as road salt used to de-ice roads, have large openings that lack doors to allow the entry of loaders and trucks to store or extract salt. Such door openings span over twenty feet in width and up to thirty feet in height and provide an adequate area for birds to enter and accumulate in the rafters therein. As is known, the collection of birds in these buildings, and pigeon lofts, and barns, etc, creates conditions that cause serious diseases, such as histoplamosis, in workers in the buildings. This is particular true when the buildings are not used for long periods of time and a large number of birds or other animals have taking up residence therein.
One method of closing these large door openings is by using a standard double hinged door. In this case, typically two doors can be swung open or closed on hinges attached to the sides of the door opening. This method has disadvantages as the door size makes the doors heavy and require a large amount of space to allow the doors to swing freely. In one case, when the doors are swung into the enclosure or building, the area to allow the door to swing open must remain clear. Hence, the door swing occupies valuable space that cannot be used to store materials. In the alternative, if the doors swing outwardly, then in cases of large snowfalls, a significant effort is necessary to clear an area to allow the doors to swing open.
A second method of closing these door openings is by using an overhead door that moves upwardly and is stored near the building ceiling. This type of door is advantageous as no space is lost for accommodating a door swing. However, an overhead door also has disadvantages, as it is extremely large, heavy and requires a track system to guide it into an open or close position. The heavy weight of the overhead door further creates additional problems in physically moving the door upward and downward. In one aspect, the weight of the door requires a significantly large motor to move the door up and down. In another aspect, the size and weight of the door represents a potential safety hazard as the moving door can cause significant injury to personnel caught in the path of a closing door. Hence, a sophisticated control system is needed to prevent a closing door from causing damage or injury. Further still, the tracks used to guide the overhead door into place are susceptible to damage by trucks or equipment operating within the building. For example, damage may occur to the track by a truck contacting a track guide. The track guide can then become mis-aligned or crimped, which can cause the overhead door to not close properly or even become disengaged from the track guide system.
An alternative type of door covering is a roll-up door, which rolls up onto a large roller suspended above the door opening. Roll-up doors typically are fabricated from a plurality of thin metal sheets, such as aluminum, steel, etc., which are hinged together to hang from a large overhead roller. The hinged metal provides flexibility for the metal sheets to collect around the suspended roller. However, while these roll-up type doors may be lighter than an overhead door, as discussed previously, the problem associated with damage to the track guides can also render these doors unfit for proper operation.
Accordingly, there is a need to provide a lightweight covering for a large door opening that allows the entry and exit of large vehicles and prevents the unwanted entry of birds, deer etc., without using a tracking guide system.
A trackless, lightweight, flexible door opening covering is disclosed. The flexible door opening covering rolls up and down on a roller mechanism which is rotatably driven by a motor mechanism, a spring loaded mechanism, a hand crank, etc. The flexible door covering is composed of a lightweight material is weighted at one end to allow the fabric to remain substantially taut as it is rolled up onto, or drawn from, the roller mechanism. Gravitation force on the weighted fabric end substantially guides the extending fabric vertically as it is drawn from the roller mechanism. In a preferred embodiment, the lightweight fabric is composed of a high-tensile strength open-weave vinyl material having finished edges. The material prevents animals from entering a building, when it is extended in front of a building opening, while allowing air circulation through the building.